Johan Harmenberg won eight individual and/or team epee gold medals at Olympic, World Championship, and World Cup competitions.

At the 1980 Moscow Olympic Games, the Swedish epee champion won a gold medal in Individual Epee.

He earned his World Championship titles in Individual Epee and Team Epee events at the 1977 competitions in Buenos Aires. He also won a bronze medal in Team Epee at the 1979 World Championships in Hamburg.

Harmenberg captured three Individual Epee World Cup Championships within four years—1977 (Bern), 1979 (Heidenheim), and 1980 (Heidenheim). He also won team honors in 1977 and 1980.